Experimental Study on Repairing Large Modulus Rack Cracks by Argon Arc Welding

The crack repair experiment with argon arc welding technology was carried out to repair large cracks in the large-module gear and rack of the shiplift. The experiment studied the influence of process parameters including welding current and prehearing temperature on the properties of the weld by using 40CrMo piece with pre-made cracks as the substrate material and TIG-R30 wire. In addition, Rockwell hardness tester and material high temperature performance tester were used to test the hardness and tensile properties of the weld. The result shows that the best performance of the welds was obtained when the welding current was 150A, the preheating temperature was 100°C and the argon flow was 15L/min. At this point, the hardness of the weld was 12.8% higher than that of the substrate with the tensile strength reaching 786Mpa, the elongation being 8% and no cracks or pores.